Luminescent polymer

ABSTRACT

A soluble luminescent polymer comprising a first repeat unit [Ar 1 ] and a second repeat unit comprising a unit of general formula (I) which is substituted or unsubstituted: wherein X is RC═CR, S, O or NR; Ar 1 , Ar 2  and Ar 3  are each independently an aromatic or heteroaromatic group; and each R independently is hydrogen or a substituent group.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage of international applicationPCT/GB01/00825, filed Feb. 26, 2001 (Patent Publication WO/01/62869),which claims the benefit of U.S. Provisional Application No. 60/207,724,filed on May 26, 2000 and Great Britain application GB 0004541.9 filedFeb. 25, 2000.

The present invention relates to a luminescent polymer, especially foruse in an optical device such as an optical device comprising anelectroluminescent device.

Electroluminescent devices are structures which emit light when subjectto an applied electric field. In its simplest form, anelectroluminescent device comprises a light-emissive layer between twoelectrodes. The cathode electrode injects negative charge carriers(electrons) and the anode electrode injects positive charge carriers(holes) into the light-emissive layer. Light emission occurs when theelectrons and holes combine in the light-emissive layer to generatephotons. As a practical aspect, one of the electrodes is typicallytransparent, to allow the photons to escape the device. Thelight-emissive layer should be made from a light-emissive material whichmay be laid down as a film without substantially affecting theluminescent characteristics of the material and which is stable at theoperational temperature of the device.

The colour of the light generated by the light-emissive material isdetermined by the optical gap or bandgap of the organic light-emissivematerial, that is to say the difference in energy between the “highestoccupied molecular orbital” (HOMO) and the “lowest unoccupied molecularorbital” (LUMO) levels. Effectively, the bandgap is the energydifference between the valance and conduction band. These levels can beestimated by photo emission measurements and measurements of theelectrochemical potentials for oxidation and reduction. The level ofthese energies is affected by numerous factors. Accordingly, the use ofsuch values is indicative rather than quantitative.

Organic electroluminescent devices which use an organic material as thelight-emissive material are known in this art. Among organic materials,simple aromatic molecules such as anthracene, perylene and corenine areknown to show electroluminescence. U.S. Pat. No. 4,539,507 discloses theuse of small molecule organic materials as the light-emissive material.

Polymers are advantageous over small molecules when used in opticaldevices because polymer devices can be made on flexible substrates andlayers of the polymer may be put down by economical coating methods. Inaddition, as discussed below, polymers have the possibility of tuningthe bandgap by structure modification.

PCT/WO90/13148 discloses an electroluminescent device comprising asemiconductor layer comprising a polymer film as the light-emissivelayer which comprises at least one conjugated polymer. In this case, thepolymer film comprises a poly (para-phenylene vinylene) (PPV) film.

It is known to use a semiconductive conjugated copolymer as thelight-emissive layer in an electroluminescent device, for example fromEP 0544795. The semiconductive conjugated copolymer comprises at leasttwo chemically different monomer units which, when existing in theirindividual homopolymer forms, typically have different semiconductorbandgaps. The proportion of the chemically different monomer units inthe copolymer can be selected to control the semiconductor bandgap ofthe copolymer so as to control the optical properties of the copolymer.To some degree, the extent of conjugation of the copolymer can be saidto affect the bandgap of the copolymer. Increasing the extent ofconjugation has the effect of decreasing the bandgap up to the point ofbandgap conversion. Therefore, selection of an appropriate polymerstructure is one way of selecting the bandgap. This gives the verydesirable feature of controlling the colour of the light output from thepolymer when made to emit light. This property is useful particularly inthe construction of electroluminescent devices.

EP 0686662 discloses a device for emitting green light. The anode is alayer of transparent indium-tin oxide. The cathode is a LiAl layer.Between the electrodes is a light-emissive layer of PPV. The devicecomprises also a hole transport layer of polyethylene dioxythiophene(PEDOT) which provides an intermediate energy level which aids the holesinjected from the anode to reach the HOMO level in the PPV.

“Efficient blue-light emitting devices from conjugated polymer blends”,Burgesson et al., Adv. Mater. 1996, 8, No. 12, pages 982-985 describes ablue-light emitting device which employs conjugated polymer blends. Theemissive layer of the device consists of a blend of PDHPT with PDPP.Light emission is from the PDHPT alone.

Few low bandgap materials are known which show good optical devicecharacteristics when used in an optical device. These characteristicsinclude the quantum efficiency when excited to luminesce, the solubilityand processability of the material and the lifetime when used in adevice. Other relevant characteristics for consideration include thestability of the polymer during use and storage of the device.

A further disadvantage associated with low bandgap materials is thatthey are difficult to make. It may be noted that polymers made byelectrochemical oxidative coupling usually are not suitable for use asemitters and in an electroluminescent device. This is because they havepoor device characteristics. For example, such polymers will have alarge number of so-called defects. Also, they are substantiallyinsoluble and are not easily processable. An example of polymers made inthis way are those disclosed in Chem. Mater. 1996, 8, page 570-578. Thepolymers disclosed therein were all obtained as insoluble deposits.Generally, the polymers disclosed in this document may be symbolised as[A-Q-A]_(n), where A is a kind of aromatic-donor unit and Q is a kind ofO-quinoid acceptor unit. The bandgaps of the disclosed polymersdetermined from optical absorption spectrum range from 0.5 to 1.4electron volts.

Macromol. Rapid. Commun. 18,1009-1016 (1997) discloses a series ofquinoxaline-based conjugated polymers which contain a ruthenium(II)bipyridine complex synthesised by the Suzuki coupling reaction. Thisdocument is particularly concerned with the desirable properties ofmetal-containing polymers and their promising applications.

Synthetic Metals, 76, (1996), 105-108 discloses a poly(phenylquinoxaline). The electron-deficient quinoxaline group is disclosed asrendering this polymer of particular interest as anelectron-transporting material for use in multi layer and composite filmelectroluminescent devices.

Despite work in the field of narrow bandgap polymers, there is still aneed for electroluminescent polymers with a chemically tuneablered-light region emission. In particular, there is a need for suchpolymers which have, additionally, excellent device characteristics asdiscussed above. For the purposes of the present invention, the phrasered-light region means wavelengths in the range of 550 nm to 800 nm.

It is an aim of the present invention to overcome the deficiencies ofthe prior art and to provide such a polymer.

It is a further aim of the present invention to provide uses of thepolymer.

Accordingly, the first aspect of the present invention provides asoluble luminescent polymer comprising a first repeat unit [Ar₁] and asecond repeat unit comprising a unit of general formula I which issubstituted or unsubstituted:

wherein X is RC═CR, S, O or NR and Ar₁, Ar₂ and Ar₃ are eachindependently an aromatic or heteroaromatic group and each Rindependently is hydrogen or any suitable substituent group.

Preferably, the first repeat unit is different from the second repeatunit.

The applicants have unexpectedly found that the structure of the presentpolymer may be selected so that the polymer acts as a low bandgapemitter when used in an optical device. Furthermore, the presentapplicants have found that the structure of the present polymer may beselected so that the polymer gives good red-light region emission, (i.e.550 nm to 800 nm) in particular 550 nm to 750 nm or as defined by theCIE coordinates X=0.66 and Y=0.33. The present polymer has propertieswhich give good device characteristics. These properties includesolubility, processability, and good efficiency and lifetime in adevice.

Organic materials having smaller optical gaps, towards the red end ofthe visible spectrum, are of particular interest to the presentinventors. It is suggested that conjugated polymers that possess narrowbandgaps will be useful not only in optical devices but also inintrinsic organic conductors, non-linear optical devices, solar cellsand IR emitters, detectors and sensors.

The present polymer does not comprise a metal complex.

Advantageously, a polymer according to the present invention hassubstantially no structural defects. In other words, it is substantiallystructurally regio regular. This is advantageous because this provides alevel of certainty insofar as different samples of the same polymer willbehave the same when used in an optical device. Usually, this willresult in a fully conjugated polymer.

In one embodiment, the polymer is excluded where X is RC═CR, and Ar₂ andAr₃ both comprise fluorene such that both fluorenes are directly bondedto the quinoxaline and the quinoxaline is one of:

Preferably, the present polymer comprises a group having a formula ashown in general formula II which is substituted or unsubstituted:

wherein X, Ar₁, Ar₂ and Ar₃ are defined as above. This arrangementincreases conjugation along the polymer backbone and may result in afully conjugated backbone.

Also, preferably, the present polymer has the following composition:

where x is 0.1 to 99.9 mol % and y is 0.1 to 99.9 mol %. It is morepreferred that x is 0.1 to 50 mol % and y is 50 to 99.9 mol %. Mostpreferably, x is 5 to 10 mol % and y is 90 to 95 mol %. These preferredcompositions have been found to result in polymers with advantageouslylow bandgaps which give good red-light region emission.

In another aspect of the present invention, preferably, the secondrepeat unit of the present polymer comprises or even consists of theunit of general formula III:

wherein R₁ and R₂ are the same or different and each comprise an H, or asubstituted or unsubstituted alkyl, aryl, heteroaryl, alkoxy, alkylaryl,arylakyl, alkoxyaryl or alkoxyheteroaryl group. Preferably, at least oneof R₁ and R₂ will comprise a substituted or unsubstituted aryl orheteroaryl group.

Selection of different substituent groups may be used to selectproperties of the polymer such as its solubility and extent ofconjugation. Thus, also, these may usefully be selected to modulate thesemiconductor bandgap of the polymer. As discussed above, this helps inHOMO/LUMO matching of the polymer with the device cathode, anode andhost material. This can tune the wavelength and quantum efficiency ofthe polymer. To this end, preferably, R₁ and R₂ may comprise one or moresubstituents independently selected from the group consisting of alkyl,aryl, perfluoroalkyl, thioalkyl, cyano, alkoxy, heteroaryl, alkylaryland arylalkyl groups. Specifically, preferred substituents of R₁ and R₂are substituted or unsubstituted phenyl groups.

Preferably, for ease of synthesis, it is envisaged that R₁ and R₂ arethe same. Furthermore, it is envisaged that, preferably, R₁ and R₂ arethe same and are each a substituted or unsubstituted phenyl group.

The selection of X being HC═CH or RC═CR where R is a substituent groupmay be used, to some extent, to select the extent of conjugation and thebandgap of the polymer and thus to tune the wavelength and quantumefficiency of the polymer. Also, this selection may be used to improvethe solubility of the polymer. Accordingly, in one preferred embodiment,X is HC═CH.

In other preferred embodiments, X is RC═CR and R comprises an alkyl,alkoxy, unfused aryl, unfused heteroaryl, aryloxy or heteroaryloxygroup. In other words, in one preferred embodiment neither R is part ofa fused ring system.

The applicants have found that Ar₁, Ar₂ and Ar₃ may advantageouslycomprise a substituted or unsubstituted, fused or unfused benzene,thiophene, furane, fluorene, triarylamine, bistriarylamine or pyridenegroup. Specifically, Ar₁, Ar₂ and Ar₃ may each independently comprise a2-3-,2-5- or 2,6-substituted benzene; 3,4-substituted thiophene;3,4-substituted furan; 9,9-disubstituted fluorene; unsubstitutedpyridene; benzo-,thio- or furano-2,3-substituted diazine; unsubstitutedphenothiodiazine; or an unsubstituted triarylamine or bistriarylaminegroup.

Advantageously, Ar₁, Ar₂ or Ar₃ each independently have one or moresubstituents. Preferred substituents include an H, amine, alkyl, aryl,heteroaryl, alkoxy, alkylaryl, arylalkyl, alkyloxy, aryloxy, alkoxyarylor alkoxyheteroaryl group.

Selection of Ar₁, Ar₂ and Ar₃ and selection of different substituentgroups on Ar₁, Ar₂ or Ar₃ may be used to select properties of thepolymer such as its solubility and extent of conjugation.

Also, these may usefully be selected to modulate the semiconductorbandgap of the polymer. As discussed above, this helps in HOMO/LUMOmatching of the polymer with the device cathode, anode and hostmaterial. This can tune the wavelength and quantum efficiency of thepolymer.

In a preferred embodiment, for ease of synthesis, Ar₂ and Ar₃ are thesame. In a further preferred embodiment, Ar₂ and Ar₃ are the same andare each an unsubstituted thiophene group. This has been found to resultin a polymer which gives particularly good red-light region emission andwhich has good efficiency and lifetime in a device.

In another preferred embodiment, Ar₁ is different from Ar₂ and Ar₃ andoptionally Ar₂ and Ar₃ are the same. Preferably, Ar₁ is a substituted orunsubstituted triarylamine group. Again, this has been found to resultin a polymer which gives particularly good red-light region emission andwhich has good efficiency and lifetime in a device.

In one embodiment, Ar₂ and Ar₃ are the same and each is not a fluorenegroup.

It is envisaged that the present polymer may further comprise a thirdrepeat unit [Ar₄] which is an aromatic or heteroaromatic group. This canbe used to maintain the extent of conjugation along the length of thepolymer backbone. Ar₄ may be the same or different from any one of Ar₁,Ar₂ and Ar₃. When the present polymer comprises a third repeat unit, itis preferred that the polymer comprises a group having a formula asshown in general formula V:

wherein Ar₁, Ar₂, Ar₃, Ar₄, R₁ and R₂ are as defined in any of the aboveembodiments.

In one further preferred embodiment, when the present polymer comprisesa third repeat unit, the polymer has the following composition:

wherein X, Ar₁, Ar₂, Ar₃, Ar₄, R₁ and R₂ as defined in any of the aboveembodiments and x is 0.1 to 99.8 mol %, y is 0.1 to 99.8 mol % and z is0.1 to 99.8 mol %. More preferably, x is around 25 mol %, y is around 25mol % and z is around 50 mol %. These preferred compositions have beenfound to result in polymers which give good red-light region emission.

The inventors have found that, in particular, polymers in accordancewith the present invention shows excellent red light emission whenexcited to luminesce. This excellent red light emission may be definedby the CIE coordinates X=0.66 and Y=0.33. Such polymers are expected tobe extremely useful as an emitter in optical devices, particularlyoptical devices comprising an electroluminescent device.

As described above, the extent of conjugation of the present polymeraffects the semiconductor bandgap of the polymer. Therefore, typicallythe polymer is at least partially conjugated or even substantially orfully conjugated.

Polymers according to the present invention provide materials with theattractive physical and processing properties of polymers and theability in their synthesis to select the aryl or heteroaryl groups andtheir substituents so as to modulate the bandgap of the polymers.

Usually, the degree of polymerisation of polymers in accordance with thepresent invention is at least three.

Preferably, polymers according to the present invention will have anaverage molecular weight of at least m_(n)=10,000. Higher molecularweight polymers have improved properties such as improved processabilityand phase separation behaviour.

Polymers according to the present invention include linear polymers,oligomers, homopolymers, copolymers and terpolymers. Preferably, thepolymer is a copolymer or terpolymer and not a homopolymer. In thisregard, a structural unit or repeat unit is distinguished from amonomeric unit. A homopolymer (i.e. prepared by polymerisation of asingle type of monomer) may be defined to have more than one differentstructural or repeat unit.

A film or coating comprising a polymer in accordance with the presentinvention also is provided.

According to a second aspect of the present invention, there is providedthe use of the present polymer as a component of an optical device.Specifically, the optical device may comprise an electroluminescentdevice.

In order for the polymer to have good device characteristics it issoluble. Substituents may usefully be selected to confer on the polymersolubility in a particular solvent system, for example for depositingthe polymer on a substrate. Typically solvents include common organicsolvents, for example toluene, xylene, THF and organic ink-jet inkformulations.

According to a third aspect of the present invention, there is providedan electroluminescent device comprising a first charge injecting layerfor injecting positive charge carriers, a second charge injecting layerfor injecting negative charge carriers, and a light-emissive layerlocated between the first and second charge injecting layers comprisinga light-emissive material for accepting and combining positive andnegative charge carriers to generate light. The light-emissive layercomprises a polymer according to the first aspect of the presentinvention for (i) transporting negative charge carriers from the secondcharge injecting layer to the light-emissive material (ii) transportingpositive charge carriers from the first charge injecting layer to thelight-emissive material or, most preferably, (iii) accepting andcombining positive and negative charge carriers to generate light.

It will be appreciated that the light-emissive layer may be formed froma blend of materials including one or more polymers according to thepresent invention, and optionally further different polymers. Asmentioned above, the one or more polymers according to the presentinvention may be included in order to improve the efficiency of holeand/or electron transport from the electrodes to the light-emissivematerial. Alternatively, it is preferred that at least one is includedas the light-emissive material itself. In this case, the blend wouldcomprise from 0.1% to 100% by weight, usually from 1 to 20% or around10% of a polymer according to this invention with the remainder of theblend comprising hole and/or electron transport polymers.

Accordingly, the present invention also provides a compositioncomprising a mixture/blend comprising one or more polymers according thefirst aspect of this invention.

Alternatively, a polymer according to the present invention may beprovided in an electroluminescent device as a discrete layer situatedbetween either the first or second charge injecting layer and a discretelayer comprising the light-emissive material. Also, it may be providedas a discrete layer which is the light-emissive material. These discretelayers optionally may be in contact with one or more (additional) holeand/or electron transporting layers.

The skilled person will know from general knowledge how to prepare firstand second repeat unit monomers in accordance with the presentinvention.

Generally speaking, polymers according to the present invention may beprepared by one of several polymerisation methods.

One suitable method, particularly for the preparation of homopolymers,is disclosed in Macromolecules, 1998, 31, 1099-1103. The polymerisationreaction involves nickel-mediated coupling of dibromide monomers. Thismethod commonly is known as “Yamamoto Polymerisation”.

Another suitable method is disclosed in U.S. Pat. No. 5,777,070. Theprocess involves contacting monomers having two reactive groups selectedfrom boronic acid, C1-C6 boronic acid ester, C1-C6 borane andcombinations thereof with aromatic dihalide functional monomers ormonomers having one reactive boronic acid, boronic acid, boranic acidester or boring group and one reactive halide functional group with eachother. This reaction is known to those skilled in this art as “SuzukiPolymerisation”.

A preferred method of preparation is described in International patentpublication No. WO 00/53656, the contents of which are incorporatedherein by reference. This describes the process for preparing a polymer,which comprises polymerising in a reaction mixture (a) an aromaticmonomer having at least two reactive boron derivative groups selectedfrom a boronic acid group, a boronic ester group and a borane group, andan aromatic monomer having at least two reactive halide functionalgroups; or (b) an aromatic monomer having one reactive halide functionalgroup and one reactive boron derivative group selected from a boronicacid group, a boronic ester group and a borane group, wherein thereaction mixture comprises a catalytic amount of a catalyst (e.g.palladium) suitable for catalysing the polymerisation of the aromaticmonomers, and an organic base in an amount sufficient to convert thereactive boron derivative functional groups into —BX₃ ⁻ anionic groups,wherein X is independently selected from the group consisting of F andOH.

Polymers according to the present invention which have been produced bythis method are particularly advantageous. This is because reactiontimes are short and residual catalyst (e.g. palladium) levels are low.

The skilled person is credited with the knowledge of knowing which ofthe above methods would be most suitable for preparing a particularpolymer in accordance with the present invention.

According to a fourth aspect of the present invention there is provideda process for preparing a polymer as defined above which comprisespolymerising in a reaction mixture:

-   (a) a first aromatic monomer comprising    -   (i) a first repeat unit as defined above; and/or    -   (ii) a second repeat unit having general formula I as defined        above,        and at least two reaction boron derivative groups selected from        a boronic acid group, a boronic ester group and a borane group;        and-   (b) a second aromatic monomer comprising the other or further of the    first and/or second repeat units and at least two reactive halide    functional groups,    wherein the reaction mixture contains a catalytic amount of a    palladium catalyst, and an organic base in an amount sufficient to    convert the reactive boron derivative groups into —B(OH)₃ anions.

A further process according to the fourth aspect of this invention forpreparing a polymer as defined above also is provided which comprisespolymerising in a reaction mixture:

-   (a) a first aromatic monomer comprising    -   (i) a first repeat unit as defined above; and/or    -   (ii) a second repeat unit having general formula I as defined        above,        and one reactive halide functional group and one reactive boron        derivative group; and-   (b) a second aromatic monomer comprising the other or further of the    first and/or second repeat units, and one reactive halide functional    group and one reactive boron derivative group, wherein each borane    derivative group is selected from a boronic acid group, a boronic    ester group and a borane group and the reaction mixture contains a    catalytic amount of a palladium catalyst, and an organic base in an    amount sufficient to convert the reactive boron derivative groups    into —B(OH)₃ ⁻anions.

According to a fifth aspect of the present invention there is provided acompound:

for use in a polymerisation reaction for the preparation of a polymer,particularly a polymer according to this invention. Also provided is theuse of the above compound for the preparation of a polymer according tothe first aspect of this invention for transporting holes and/orelectrons and/or for accepting and combining holes and electrons togenerate light in an optical device. The first and second repeat unitsin this compound are as defined in relation to any aspect or embodimentof this invention described above, x may be 0 or 1 and E and E¹ are thesame or different and are reactive groups capable of undergoing chainextension.

Preferably, E and E¹ are the same or different and are selected from thegroup consisting of a reactive halide functional group and a reactiveboron derivative group. More preferably, the reactive halide functionalgroup is selected from the group consisting of F, Cl, Br or I and theborane derivative group is selected from the group consisting of aboronic acid group, a boronic ester group or a borane group.

The present invention now will be described in more detail withreference to the accompanying drawings in which:

FIG. 1 is a schematic diagram of an optical device according to thepresent invention.

One preferred polymer in accordance with the present invention is thepolymer having composition:

One example of a blend including a polymer according to the presentinvention that could be used in an electroluminescent device is a blendof the preferred polymer according to this invention referred to abovewith a dioctylfluorene benzothiadiazole polymer andpoly(2,7-(9,9-di-n-octylfluorene)-(1,4-phenylene-((4-secbutylphenyl)imino)-1,4-phenylene)(“TFB”).

EXAMPLES Example 1 Preparation of the Polymer

A suspension of 9,9-dioctylfluorene-diester (4.82 g, 9.09 mmol),dibromo-benzothiodiazine (1.323 g, 4.5 mmol), “trimer 1” (2.720 g, 4.5mmol) and tetrakis (triphenyl phosphine) palladium (0) (30 mg) intoluene (90 mL) was de-gased with nitrogen. After 1 hour, tetraethylammonium hydroxide (30 mL) was added to the reaction mixture and thesuspension heated to ˜115° C. (external temp.). The reaction wasend-capped with bromobenzene (15 mL) after 20 hours. Stirring wasmaintained at 115° C. for 1 hour then phenyl boronic acid (2.5 g) wasadded and stirring continued for a further 1.5 hours. Once the reactionmixture had cooled to r.t. the polymer was precipitated into methanol(4L). The polymer was filtered off and re-dissolved in toluene (500 mL).A solution of dithiocarbamic acid (30 g) in H₂O (220 mL) was added tothe toluene solution. The salt mixture was heated to 65° C. for 18 hoursand then the aqueous layer was removed. The organic phase was passeddown an alumina/silica column, eluting the polymer with toluene. Thetoluene was condensed to 350 mL and then precipitated into methanol(4L). The polymer was filtered off and dried thoroughly. The yield was62%.

Example 3 Electroluminescent Device

A suitable device structure is shown in FIG. 1. The anode 2 is a layerof transparent indium-tin oxide (“ITO”) supported on a glass or plasticsubstrate 1. The anode 2 layer has a thickness between 1000-2000 Å,usually about 1500 Å. The cathode 5 is a Ca layer having an approximatethickness of 1500 Å. Between the electrodes is a light emissive layer 4having a thickness up to about 1000 Å. The emissive layer 4 comprisesbetween 0.5 to 30% by weight of the present polymer with the remainderof the emissive layer consisting of hole and/or electron transportmaterial. Advantageously, the device includes a hole transport materiallayer 3 of PEDOT having a thickness of about 1000 Å. Layer 6 is anencapsulant layer of a suitable thickness.

1. A method of making a polymer comprising polymerizing a compoundhaving general formula VII:

where x=0 or 1 and E and E¹ are the same or different and are reactivegroups capable of undergoing chain extension and where the first repeatunit has formula [Ar₁] and the second repeat unit comprises a unit ofgeneral formula I which is substituted or unsubstituted:

wherein X is RC═CR, S, O or NR; Ar₁, Ar₂ and Ar₃ are each independentlyan aromatic or heteroaromatic group; and each R independently ishydrogen or a substituent group.
 2. A method according to claim 1,wherein the first repeat unit is different from the second repeat unit.3. A method according to claim 1, which comprises a group having aformula as shown in general formula II which is substituted orunsubstituted:

wherein X, Ar₁, Ar₂ and Ar₃ are as defined in claim
 1. 4. A methodaccording to claim 1, wherein the second repeat unit comprises a unit ofgeneral formula III:

wherein R₁ and R₂ are the same or different and each comprise an H or asubstituted or unsubstituted alkyl, aryl, heteroaryl, alkoxy, aryloxy,alkylaryl, arylakyl, alkoxyaryl or alkoxyheteroaryl group.
 5. A methodaccording to claim 4, wherein R₁ and R₂ are the same and each asubstituted or unsubstituted phenyl group.
 6. A method according toclaim 1, wherein X is HC═CH.
 7. A method according to claim 1, whereinAr₁, Ar₂ and Ar₃ each independently comprise a substituted orunsubstituted, fused or unfused benzene, thiophene, furan, fluorene,triarylamine, bistriarylamine or pyridine group.
 8. A method accordingto claim 1, wherein Ar₂ and Ar₃ are the same.
 9. A method according toclaim 8, wherein Ar₂ and Ar₃ are each an unsubstituted thiophene group.10. A method according to claim 1, wherein Ar₁ is a substituted orunsubstituted triarylamine group.
 11. A method according to claim 1where E and E¹ are the same or different and are selected from the groupconsisting of a reactive halide functional group and a reactive boronderivative group.
 12. A method according to claim 11 where the reactivehalide functional group is selected from the group consisting of F, Cl,Br and I and the boron derivative group is selected from the groupconsisting of a boronic acid group, a boronic ester group and a boranegroup.
 13. A soluble luminescent polymer comprising a first repeat unit(Ar₁) and a second repeat unit; wherein Ar₁ is selected from the groupconsisting of a substituted or unsubstituted, fused or unfused benzene,thiophene, furan, fluorene, triarylamine, bistriarylamine or pyridinegroup, and the second repeat unit is selected from the group consistingof a unit of general formula I which is substituted or unsubstituted:

wherein X is RC═CR, S, O or NR; Ar₁, Ar₂ and Ar₃ are each independentlyan aromatic or heteroaromatic group; and each R independently ishydrogen or a substituent group; or a unit of general formula III:

 wherein R3 and R2 are the same or different and each comprise an H or asubstituted or unsubstituted alkyl, aryl, heteroaryl, alkoxy, aryloxy,alkylaryl, arylalkyl, alkoxyaryl or alkoxyheteroaryl group and whereinAr₁ is different from Ar₂ and Ar₃.
 14. A polymer according to claim 13which comprises a third repeat unit [Ar₄] which is an aromatic orheteroaromatic group and is different from Ar₁, Ar₂ and Ar₃.
 15. Apolymer according to claim 14, which comprises a group having a formulaas shown in general Formula V:


16. A polymer according to claim 14, having the following composition:


17. A process for preparing a luminescent polymer as defined in claim13, which comprises polymerizing in a reaction mixture: (a) a firstaromatic monomer comprising (i) a first repeat unit (Ar₁) is selectedfrom the group consisting of a substituted or unsubstituted, fused orunfused benzene, thiophene, furan, fluorene, triarylamine,bistriarylamine or pyridine group; and/or (ii) a second repeat unithaving a general formula is selected from the group consisting of a unitof general formula I which is substituted or unsubstituted:

wherein X is RC═CR, S, O or NR; Ar₁, Ar₂ and Ar₃ are each independentlyan aromatic or heteroaromatic group; and each R independently ishydrogen or a substituent group; or a unit of general formula III:

 wherein R₁ and R₂ are the same or different and each comprise an H or asubstituted or unsubstituted alkyl, aryl, heteroaryl, alkoxy, aryloxy,alkylaryl, arylalkyl, alkoxyaryl or alkoxyheteroaryl group;  and atleast two reactive boron derivative groups selected from a boronic acidgroup, a boronic ester group and a borane group; and (b) a secondaromatic monomer comprising the other or further of the first or secondrepeat units and at least two reactive halide functional groups, whereinthe reaction mixture contains a catalytic amount of a catalyst, and anorganic base in an amount sufficient to convert the reactive boronderivative groups into —B(OH)₃ anions.
 18. A process for preparing aluminescent polymer as defined in claim 13, which comprises polymerizingin a reaction mixture: (a) a first aromatic monomer comprising (i) afirst repeat unit (Ar₁) is selected from the group consisting of asubstituted or unsubstituted, fused or unfused benzene, thiophene,furan, fluorene, triarylamine, bistriarylamine or pyridine group; and/or(ii) a second repeat unit having general a formula is selected from thegroup consisting of a unit of general formula I which is substituted orunsubstituted:

wherein X is RC═CR, S, O or NR; Ar₁, Ar₂ and Ar₃ are each independentlyan aromatic or heteroaromatic group; and each R independently ishydrogen or a substituent group; or a unit of general formula III:

 wherein R₁ and R₂ are the same or different and each comprise an H or asubstituted or unsubstituted alkyl, aryl, heteroaryl, alkoxy, aryloxy,alkylaryl, arylalkyl, alkoxyaryl or alkoxyheteroaryl group;  and onereactive halide functional group and one reactive boron derivativegroup; and (b) a second aromatic monomer comprising the other of thefirst or second repeat units and one reactive halide functional groupand one reactive boron derivative group, wherein each borane derivativegroup is selected from a boronic acid group, a boronic ester group and aborane group and the reaction mixture comprises a catalytic amount of acatalyst, and an organic base in an amount sufficient to convert thereactive boron derivative groups into —B(OH)₃ anions.
 19. An opticaldevice or a component therefore, which comprises a substrate and apolymer as defined in claim 13, supported on the substrate.
 20. Anoptical device or a component therefore, according to claim 19, whereinthe optical device comprises an electroluminescent device.
 21. Anelectroluminescent device according to claim 20 comprising: a firstcharge injecting layer for injecting positive charge carriers; a secondcharge injecting layer for injecting negative charge carriers: alight-emissive layer located between the first and second chargeinjecting layers comprising a light-emissive material for accepting andcombining positive and negative charge carriers to generate light:wherein the light-emissive layer comprises a polymer as defined in claim14 for (i) transporting positive and/or negative charge carriers fromthe first and/or second charge injecting layer to the light-emissivematerial or (ii) accepting and combining positive and negative chargecarriers to generate light.
 22. A composition comprising a mixturecomprising a polymer as defined in claim
 13. 23. A compound for thepreparation of a polymer having general formula VII:

where x =1 and E and E¹ are the same different and are reactive groupscapable of undergoing chain extension and where the first repeat unithas formula [Ar] and the second repeat unit comprises a unit of generalformula I which is substituted or unsubstituted:

wherein X is RC═CR, S, O or NR; Ar₁, Ar₂ and AR₃ are each independentlyan aromatic or heteroaromatic group; and each R independently ishydrogen or substituent group.
 24. A compound according to claim 23,wherein the first repeat unit is different from the second repeat unit.25. A compound according to claim 23, wherein the second repeat unitcomprises a unit of general formula III:

wherein R₁ and R₂ are the same or different and each comprise an H or asubstituted or unsubstituted alkyl, aryl, heteroaryl, alkoxy, aryloxy,alkylaryl, arylalkyl, alkoxyaryl or alkoxyheteroaryl group.
 26. Acompound according to claim 23, wherein R₁ and R₂ are the same and eacha substituted or unsubstituted phenyl group.
 27. A compound according toclaim 23, wherein X is HC═CH.
 28. A compound according to claim 23,wherein Ar₁, Ar₂ and Ar₃ each independently comprise a substituted orunsubstituted, fused or unfused benzene, thiophene, furan, fluorene,triarylamine, bistriarylamine or pyridine group.
 29. A compoundaccording to claim 23, wherein Ar₂ and Ar₃ are the same.
 30. A compoundaccording to claim 23, wherein Arand Ar₃ are each an unsubstitutedthiophene group.
 31. A compound according to claim 23, wherein Ar₁ is asubstituted or unsubstituted triarylamine group.
 32. A compoundaccording to claim 23 where E and E¹ are the same or different and areselected from the group consisting of a reactive halide functional groupand a reactive boron derivative group.
 33. A compound according to claim23 where the reactive halide functional group is selected from the groupconsisting of F, Cl, Br and the boron derivative group is selected fromthe group consisting of a boronic acid group, a boronic ester group anda borane group.
 34. A method of making a polymer comprising polymerizinga compound having general formula VII:

where x =0 or 1 and E and E¹ are the same or different and are reactivegroups capable of undergoing chain extension and where the first repeatunit has formula [Ar₁] and the second repeat unit comprises a unithaving one of the formulas:

wherein X′ is S, O or NR; Ar₁ is an aromatic or heteroaromatic group;and Ar₂ and Ar₃ are fluorene.